High performance door

ABSTRACT

A high performance door comprising a door shell having a generally planar construction with marginal edges and at least one door skin helping to define an interior door cavity and a door member disposed within the interior door cavity is disclosed. The door member is preferably constructed of a gas-entrained cementitious material and has a compressive strength of at least about 30 lbf/in 2  when measured using ASTM C-39. A method for forming a door member for use in construction with the door generally comprising: providing a door shell, placing the door shell in a fixture, filling the interior door cavity with a gas-entrained cementitious material, green-strength curing the gas-entrained cementitious material, and removing the door shell from the fixture is disclosed. The cured gas-entrained cementitious material provides a gas-entrained cementitious core for use in conjunction with a door.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention is directed to a high performance door, and more specifically, a high performance door that has a gas-entrained cementitious core.

[0003] 2. Background Art

[0004] Several applications for residential and commercial entry way doors require high levels of performance. For example, rated fire doors, security doors, high insulation doors, rated sound transmission reduction doors, and rated weather-resistant doors have been manufactured for many years. The typical high performance door, as well as other types of doors, include face surfaces, edge surfaces, core materials, and adhesives. The face surfaces function as an aesthetic layer, a barrier to light in the infrared and visible wavelengths, a barrier to rain and wind, a stiffening member, and a barrier to fire. The edge surfaces, through the use of adhesives, act as a connecting element between the face surfaces. In addition, the edge surfaces act as a substrate for lock and hinge hardware. In conjunction with the face surfaces, the edge surfaces act as a sealing surface for weather stripping. The edge surfaces also serve as a stiffening member, a door reinforcement, and a mating substrate connector. The core material serves as a stiffening member, a connecting element between the face surfaces, a barrier to light in the infrared and visible wavelengths, a provider of bulk mass, and a barrier to fire. The elements of the high performance door may have one element that serves multiple purposes.

[0005] Current designs of high performance doors are either substantially more costly than conventional doors and/or have limited efficacy. For example, steel doors are often used as rated fire doors. However, steel doors rust when not maintained, dent readily, and transmit heat readily during fire tests. When filled with polyurethane or expanded polystyrene foam cores, the steel doors cannot pass standard 20 or 30 minute positive pressure fire rating tests (ASTM 2074-00, UL 1° C., UBC 7-2-1997 test or British Standard 476, Section 22, hereinafter referred to as BSI 476/22) without affixing expensive intumescent seals to the steel door frame. In addition, decorative panels with sharp embossments, a feature highly desired by customers, typically cannot be stamped into steel door skins.

[0006] Wood fire doors are typically heavy since they typically incorporate a fire retardant core. The wood door faces will split or crack if not maintained, and are generally unsuitable for weather exposure for extended times due to moisture variations and damage from the sun's ultraviolet rays. Moreover, wood fire doors typically do not act as sufficient thermal insulators.

[0007] Fiberglass fire doors have been made with polyurethane foam/gypsum board cores, mineral cores, and phenolic foam. These doors are typically resistant to rusting, denting, cracking, and splitting and require relatively low maintenance. However, fiberglass fire doors regularly fail positive pressure fire tests. In addition, fiberglass fire doors are substantially more expensive than existing steel fire doors.

[0008] High insulation doors have been manufactured for many years. High insulation doors conserve energy in residences and save lives during fires, especially in institutions serving the physically handicapped. In designing high insulation doors, one of the major considerations is the stiffness of the door. To enhance the stiffness in many high insulation doors, foamed rigid polyurethane is commonly used as a core material. Even though foamed rigid polyurethane is typically used, it suffers from relatively low compression strength (from about 16 lbf/ft² to about 20 lbf/ft²), a relatively low Young's modulus of about 25,000 lbf/in², and a relatively low sound transmission coefficient of 28 or less for rigid polyurethane foams with densities of about 2.1 lb/ft³ to about 2.4 lb/ft³. Changing the formulation of polyurethane foams to enhance stiffness and sound protection typically results in higher costs due to added materials necessary for fabrication, especially the use of expensive aromatic ring compounds.

[0009] Conventional high insulation doors suffer from certain performance limitations. Most high insulation doors used in residences are filled with foams of thermoplastic or thermoset organic polymers. These doors have a relatively low u-factor of less than 0.50. In addition, these doors do not perform well during extended exposure to fire.

[0010] Current designs of high insulation doors generally require stiff skins of metal or fiberglass to provide the structural strength that is typically necessary for residential applications. Stiff skins are generally more expensive than other aesthetic surfaces, therefore high insulation doors composed of stiff skins typically cost more than other residential doors. Moreover, these doors are lighter in weight than wood doors. Since consumers correlate increased weight with increased quality and security, consumers are not drawn to high insulation doors that are lighter than wood doors. High insulation doors commonly provide insufficient resistance to sound transmission for use in areas requiring sound transmission coefficients that exceed about 28, for example, in light commercial buildings near airports.

[0011] It would be desirable to provide a high performance door with a gas-entrained cementitious core that is relatively inexpensive to manufacture, passes positive pressure fire tests, resists rusting, denting and cracking, and requires relatively low maintenance. It would also be desirable to provide a method for manufacturing a high performance door with the above-mentioned attributes.

SUMMARY OF THE INVENTION

[0012] The high performance doors of the present invention provide a gas-entrained cementitious core that is relatively inexpensive to manufacture, passes positive pressure fire tests, resisting rusting, denting, and cracking, and requires relatively low maintenance. The methods of the present invention provide a means of manufacturing the high performance doors of the present invention with the above-mentioned attributes.

[0013] One aspect of the present invention is a high performance door comprising a door shell having a generally planar construction with marginal edges and at least one door skin helping to define an interior door cavity and a door member disposed within the interior door cavity. The door member is constructed of a gas-entrained cementitious material. Preferably, the door member has a compressive strength of at least 30 lbf/in² when measured using ASTM C-39.

[0014] Another aspect of the present invention is a method for forming a door member for use in construction with a door. The method generally comprises providing a form having a generally planar construction, filling the form with a gas-entrained cementitious material, green-strength curing the gas-entrained cementitious material, and removing the cured gas-entrained cementitious material from the form. The material used to construct the form does not readily adhere to the gas-entrained cementitious material. The cured gas-entrained cementitious material provides a gas-entrained cementitious core for use in conjunction with the door.

[0015] Yet another aspect of the current invention includes a method for forming a door member for use in conjunction with a door that comprises selecting a gas-entrained cementitious material, casting the gas-entrained cementitious material into a form, allowing the gas-entrained cementitious material to achieve green-strength cure, and removing the gas-entrained cementitious material from the form. The gas-entrained cementitious material preferably has a flowability of between about 4.825 inches and about 18 inches when tested using the TT flowability method. The cured gas-entrained cementitious material provides a gas-entrained cementitious core for use in conjunction with the door.

[0016] Another aspect of the present invention includes a method for forming a high performance door. The method is generally comprised of providing a door shell having a generally planar construction with marginal edges and at least one door skin helping to define an interior door cavity, placing the door shell in a fixture, filling the interior door cavity with a gas-entrained cementitious material, green-strength curing the gas-entrained cementitious material, and removing the door shell from the fixture. The cured gas-entrained cementitious material provides a gas-entrained cementitious core for use in conjunction with the door.

[0017] These and other objects of the present invention will become more apparent from a reading of the specification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a front elevational view of a high performance door according to one embodiment of the present invention;

[0019]FIG. 2 illustrates a method for forming a gas-entrained cementitious core according to one embodiment of the present invention;

[0020]FIG. 3 illustrates a method for securing a casing over a door member according to one embodiment of the present invention;

[0021]FIG. 4 illustrates an aesthetic layer applied to a door member according to one embodiment of the present invention;

[0022]FIG. 5 is a front elevational view of a high performance door constructed with a pre-pigmented plastic shell showing a stile insert for securing two hinge plates and a lock box insert for engaging a lock box according to one embodiment of the present invention;

[0023]FIG. 6 is a front elevational view of the high performance door constructed with a pre-pigmented plastic shell showing two sets of inserts for securing two hinge plates and the lock box insert for engaging the lock box according to one embodiment of the present invention;

[0024]FIG. 7 is an exploded view of a set of inserts for engaging a hinge plate according to one embodiment of the present invention;

[0025]FIG. 8 illustrates a method for filling high performance doors with a gas-entrained cementitious core according to one embodiment of the present invention; and

[0026]FIG. 9 illustrates a method for removing excess gas-entrained cementitious material from an interior door cavity according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0027] The present invention will now be described in detail with reference being made to the accompanying drawings. Referring to FIG. 1, door 10 is illustrated. According to the preferred embodiment illustrated in FIG. 1, door 10 is a hinged entry way door. It is understood that door 10 refers to, but is not limited to, hinged patio doors, sliding patio doors, hinged interior doors, residential fire doors (house-to-garage) with neutral or positive pressure test ratings of up to 90 minutes, commercial fire doors with ratings of up to 180 minutes, commercial fire doors with restricted temperature rise in 30 minutes of less than 450° F., security-rated doors with ratings between grade 20 and 40 according to ASTM F-476, impact-resistant doors suitable for meeting high wind velocity building codes, general commercial grade doors, segmented and unsegmented garage doors and sound transmission resistant doors. According to the preferred embodiment illustrated in FIG. 1, door 10 includes door member 12 and door shell 14. The door member 12 is preferably comprised of a gas-entrained cementitious core. A gas-entrained cementitious material is preferably used to construct the gas-entrained cementitious core. The gas-entrained terms, as used as related concepts, are discussed in greater detail below. The door shell 14 helps to define interior door cavity 16. The door shell 14 can be comprised of fiberglass, for example, as disclosed and incorporated by reference in U.S. Pat. Nos. 4,550,540 and RE 36,240.

[0028] As shown in FIG. 1, door shell 14 includes first door skin 18, second door skin 20, and door frame 22. Door frame 22 includes a first stile 24 and a second stile 26. Stiles 24 and 26 are parallel to one another. Stiles 24 and 26 are positioned in a perpendicular relationship to first rail 28 and second rail 30. Second rail 30 is parallel to and spaced apart from first rail 28. First rail 28 and second rail 30 extend between and connect to stiles 24 and 26. It is understood that first rail 28 may be connected to stiles 24 and 26 after door member 12 is inserted into interior door cavity 16. According to FIG. 1, door frame 22 has a rectangular geometric configuration. However, it is understood that door frame 22 can be arranged in a variety of geometric configurations depending upon the desired application. For example, door frame can have a radiused or arched top typical of “mission style” architecture. Door 10 can have a thickness of between about 0.5 inches and about 3 inches. Preferably, door 10 has a thickness of between about 1.25 inches and about 1.85 inches. Door 10 can have a height of between about 48 inches and about 200 inches. Door heights of about 150 inches to about 200 inches are preferred for construction of custom arthitectural door panels. Preferably, door 10 has a height of between about 74 inches and about 96 inches. Door 10 can have a width of between about 8 inches and about 48 inches. Preferably, door 10 has a width of between about 10 inches and about 44 inches. Most preferably, door 10 has a width of between about 30 inches and about 42 inches.

[0029] As shown in FIG. 1, stiles 24 and 26 and rails 28 and 30 are made of laminated wood. Alternatively, untreated wood can be coated with a sealant, preferably PERMAX 803, to restrict water efflux through the wood which could possibly stain stiles 24 and 26 and rails 28 and 30 and could possibly change the water to cement ratio in the gas-entrained cementitious material. It is also understood that unlaminated wood may be utilized to construct stiles 24 and 26 and rails 28 and 30. In addition, it is understood that stiles 24 and 26 and rails 28 and 30 can be made of any other material capable of blocking the migration of the gas-entrained cementitious material out of edge faces 32. Stiles 24 and 26 can also be a hollow channel of pultruded or extruded reinforced plastic, a metal hollow channel, a partially or totally metal reinforced channel made of a material other than metal, or a compressed mineral stile. Moreover, a plurality of nails 34 can be inserted into the interior edges of the stiles prior to filling the interior door cavity with the gas-entrained cementitious material. The nails 34 serve to connect the door frame 22 to the gas-entrained cementitious core.

[0030] As depicted in FIG. 1, first door skin 18 is secured to a first side of door frame 22 and second door skin 20 is secured to a second side of door frame 22. Preferably, first door skin 18 and second door skin 20 are secured to door frame 22 with adhesive. In one embodiment of the present invention, door skins 18 and 20 are constructed of fiberglass and can be secured to door frame 22 with adhesive or mating surfaces. However, it is understood that door skins 18 and 20 can include interlocking edges that function to secure door skins 18 and 20 to door frame 22. Alternatively, an interlocking skin can be used, instead of first door skin 18 and second door skin 20. The interlocking door skin fits over the door frame 22 and the edges of the interlocking door skin mate together through the use of snap-fits.

[0031] As shown in FIG. 1, reinforcement mat 36 can be placed within the door frame 22 for additional strength. The reinforcement mat 36 can be fastened to the inside edges of the door frame 22 using nails 38 or any other fastener means. However, it is understood that the reinforcement mat 36 can be placed within the door frame 22 without fasteners, and may be fastened to articles other than the door frame such as interlocking edges of the skins or purpose-designed holding fixtures. In this example, the gas-entrained cementitious material is placed around the reinforcement mat 36 and secures the reinforcement mat 36 within the interior door cavity 16 upon curing. The material used to construct the reinforcement mat 36 can vary depending on the application. For example, reinforcement mat materials can include metal mesh, such as chicken wire, grill cloth, aluminum screen, expanded metal, or chain-link fence; polymeric mesh, such as ultra-high weight molecular polyethylene; construction fencing; aramid fiber mat; glass fiber mat (needled, woven, or non-woven); carbon fiber mat; nylon screen; rubber-coated textiles; and plastic laminated fibers. In addition, solid metal, textile or polymeric sheets of smaller dimensions than the door frame 22 can be used as reinforcement mat materials. The solid material has smaller dimensions than the door frame 18 so that the gas-entrained cementitious material is not segmented during pouring and curing.

[0032]FIG. 1 illustrates that first hinge insert 40, second hinge insert 42, and lock insert 44 can be inserted into the door shell 14 prior to pouring the gas-entrained cementitious material into the interior door cavity 16. Hinge inserts 40 and 42 can be fastened to second stile 26, adhered to either or both first door skin 18 or second door skin 20, or inserted into pre-defined spaces in either or both first door skin 18 or second door skin 20. Lock insert 44 can be fastened to first stile 24, adhered to either or both first door skin 18 or second door skin 20, or inserted into pre-defined spaces in either or both first door skin 18 or second door skin 20. Inserts 40, 42, and 44 can also be inserted after the gas-entrained cementitious material has been poured, but before it has cured. First hinge plate 46 and second hinge plate 48 can be secured to first hinge insert 40 and second hinge insert 42 by using a screw, nail, or similar fastener. Lock apparatus 50 can be secured to lock insert 44 by using a screw, nail or similar fastener.

[0033] The door member 12 can be made of a variety of materials using a variety of processes depending on the application. For example, the door member 12 can be constructed of the gas-entrained cementitious material, preferably a controlled low strength cementitious material, more preferably an air-modified controlled low strength cementitious material, and most preferably a foamed cement slurry.

[0034] Gas-entrained cementitious materials refer to inorganic materials or mixtures of inorganic materials which sets and develops strength by a chemical reaction with water by formation of hydrates, and which entrains more than about 5 volume % gas, preferably between about 10 and about 80 volume %, more preferably between about 30 and about 60 volume %, and most preferably between about 40 and about 55 volume %. It is understood that the gas can come from a variety of sources including, but not limited to direct gas injection, microspheres containing gases, porous particles containing gases, and in-situ chemical reactions or changes in the state of matter. It is further understood that materials entrained may not always be in the gaseous phase, particularly when environmental temperatures to which the article is exposed change significantly. It is further understood that the gases may migrate through time and be replaced by other gases or liquids.

[0035] Controlled low strength cementitious material (CLSM), a subset of gas-entrained cementitious materials, refers to a generic term for flowable cementitious materials having a self-compacting property and a strength of less than 1,200 lbf/in² (8.27 MPa), preferably an unconfined ultimate compressive strength of 30-500 lbf/in², and most preferably an unconfined compressive strength of 50-250 lbf/in². CLSMs are also commonly referred to as flowable fill, flow fill, or controlled density fill.

[0036] Air-modified controlled low strength cementitious materials refer to a CLSM which has entrained in it more than 5 volume % air, preferably between about 10 to about 80 volume % air, more preferably between about 30 to about 60 volume % air, and most preferably about 40 to about 55 volume % air.

[0037] Foamed cement slurries refer to a type of air-modified controlled low strength cementitious material in which the cementitious material is any type of hydraulic cement, most preferably Portland cement, in which air or other gases are entrained at more than 5 volume % air or other gas, preferably between about 10 to about 80 volume % air or other gas, more preferably between about 30 to about 60 volume % air or other gas, and most preferably between about 40 to about 55 volume % air or other gas. Portland cement is defined in ASTM C-150 and is a variety of blended hydraulic cement as defined in ASTM C-595.

[0038] Foamed cement slurries are most preferably utilized to produce gas-entrained cementitious cores by transferring the foamed cement slurry into the interior door cavity 16. The foamed cement slurry is prepared by mixing hydraulic cement, water, and a foaming agent. Typically, air and water are mixed with the foaming agent to produce a foaming solution with entrained air. Once the foamed cement slurry is cured, the entrained air inhibits freeze-thaw spalling of the gas-entrained cementitious core. Once mixed, the foamed cement slurry can be transferred into the interior door cavity 16. Preferred methods for transferring the foamed cement slurry into the interior door cavity are discussed in more detail below. Preferably, the water to cement ratio in the foamed cement slurry is greater than about 38 parts water to about 100 parts cement by weight. If the ratio falls short of 0.38, the resulting door member can be unacceptably weak. Additional additives, such as water reducers, setting accelerators, superplasticizers, reinforcement fibers, and expanded polystyrene beads, can be added to the foamed cement slurry to enhance properties, such as flow rate, curing rate, weight, or rigidity. It should be understood that reinforcing fibers refer to a fiber or a bundle of fibers having an aspect ratio greater than 4, which results in one or more increased mechanical properties when present.

[0039] Water reducers, in general, improve the workability of cement slurries and reduce the amount of mixing water for a given workability. Typically this is about 5-15% reduction in water usage. Water reducers are frequently drawn from the groups consisting of condensed naphthalene sulfonic acids, salts of lignosulfonic acids, salts of hydroxycarboxylic acids, carbohydrates and blends thereof. Superplasticizers, also known as superfluidizers, super water reducers, and high range water reducers, are a class of water reducers capable of reducing the water usage by at least about 30%. While not wanting to be bound by any one theory, it is believed that superplasticizers break down the large irregular agglomerates of cement particles by virtue of deflocculation due to adsorption and electrostatic repulsion, as well as some steric effects. Superplasticizers are typically drawn from a group consisting of sulfonated melamine-formaldehyde condensates, sulfonated naphthalene-formaldehyde condensates, modified lignosulfonates, sulfonic acid esters, polyacrylates, polystyrene sulfonates, and blends thereof.

[0040] Many cements that are suitable for use in the present invention contain additives. These additives can include cementitious and pozzolanic additives. Cementitious additives refer to an inorganic material or mixture of inorganic materials which forms or assists to form cementitious materials which develops strength by chemical reaction with water by formation of hydrates. Cementitious additives are generally rich in silica and alumina. According to ASTM C-539-94, pozzolanic additives refer to siliceous or alumino-siliceous material which in itself possesses little or no cementitious value, but which when in finely divided form and in the presence of moisture will chemically react with alkali and alkaline earth hydroxides at ordinary temperatures to form or assist in forming compounds possessing cementitious properties. Examples of pozzolanic additives can include Class C fly ash from burning lignite coal, Class F fly ash from burning bituminous coal, pulverized-fuel fly ash, condensed silica fume, metakaolin, rubber ash, and glass cullet. Additives found in cement are particularly useful in increasing the mass of the resulting door member.

[0041] Insulating gases can replace entrained air to provide greater insulation. These gases include molecules that generally have a higher atomic mass than air. Possible examples include halocarbons and hydrohalocarbons, such as HCFC-22, HFC-134a, HFC-245fa, HFC-365mfc; noble gases, such as argon, xenon, and krypton; sulfur hexafluoride; hydrocarbons, such as pentane; and mixtures thereof. The process of introducing the insulating gas into the foamed cement slurry is discussed below.

[0042] Door members 12 can be formed without the use of a door shell 14. As shown in the embodiment depicted in FIG. 2, slabs of concrete or cement that have relatively low slump values and relatively low flow rates can be cast. Suitable foamed cement slurries for this purpose include those that have a flowability of about 4.825 inches to about 18 inches using the TT flowability method. The TT flowability method includes preparing a close-ended box from pressure-treated Southern Yellow Pine that includes a reservoir. The box is treated with polyvinylidene chloride, preferably PERMAX 803, for sealing purposes. The box is preferably at least 26 inches long. The reservoir is preferably a 6 inches×6 inches×6 inches cube with a non-porous slide gate leading to the flow channel. The box is placed on a level surface. The foamed cement slurry to be tested for flowability is poured into the reservoir, and screed off even with the 6 inch high mark. The slide gate is opened with any adhering foamed cement slurry scraped off into the reservoir. The foamed cement slurry is allowed to flow into the channel. The furthest distance of flow from the slide gate is measured after 1.0 minute.

[0043] The slabs are formed by pouring a suitable foamed cement slurry 60 with a relatively low slump value and relatively low flow rate through nozzle 62 into a form 64, preferably an open-faced form. The open-faced form is preferably placed on a horizontal belt 66 before the foamed cement slurry 60 is poured. Mechanical spreader 68 is preferably used to distribute the foamed cement slurry in the open-faced form and to prepare the cured foamed cement slurry for the door frame. Other suitable devices to distribute and prepare the foamed cement slurry include screes and embossment units. Once the foamed cement slurry is cured, the resulting door member is released from the open-faced form. The form can be constructed of ultrahigh molecular weight polyethylene, high density polyethylene, polypropylene, polycarbonate, polyvinylidene chloride or any other material that does not readily adhere to the foamed cement slurry. The Hardie Plank machine, available from James Hardie Company of Australia can be used to form continuous casting slabs of polymer cement board. In addition, the Cemplank machine or the Cembord machine, both available from Cemplank, Inc. of Blandon Pa. can be used to form continuous casting slabs of polymer cement board.

[0044] Door members that are cast in the open-faced form can be secured to a door shell through adhesives. Securing means are understood to include, but be limited to, fasteners, adhesives, snap-fits, plastic or metal welding, interlocks, and pressure fit devices.

[0045] For example, as illustrated in FIG. 3, casing 72 can be secured over the door member 74. Casings are understood to mean vessels for receiving core materials where marginal edges are present or may be formed by temporary external means and the second skin surface is either attached on at least once side to the marginal edge or may be connected in a subsequent process step. Casings are understood to include, but are not limited to, multi-sided pans with lids, tubes, tubes that conform to temporary external fixtures, bags, cassettes with multiple sides that fold, fold-over or that are pre-folded and secured with a top flap that is secured in a subsequent process step.

[0046] As illustrated in FIG. 4, an aesthetic layer 78 can be applied to the door member 80. Examples of a specific type of aesthetic layers, wood-like aesthetic surface layers, can include wood veneers, decorative films that simulate wood finishes, transcribed pigment layers, polyvinylidene chloride coated wood and organic polymer coating. An example of a decorative film that simulates a wood finish is an extruded sheet containing dyes that liquefy at different temperatures, as disclosed in U.S. Pat. No. 5,866,054. An example of a transcribed pigment layer is FINAL FINISH, a product available from Immersion Graphics, Inc. of Columbus, Ga. It is understood that prior to applying the wood-like aesthetic surface layer, a finish sanding or other smoothing process can be utilized to minimize minor imperfection on the surface of the door member. A wood-like texture can be molded into the door member. Many processes exist to produce wood-like textures. For example, a silicone rubber or polymer film master can be constructed from a model door skin. In addition, the following processes can be utilized: an acid-etched steel master can be constructed from a photoresist, nickel chemical vapor deposition can be utilized, and hand or machine engraved masters of wood, metal, ceramic, or polymer can be used.

[0047] Moreover, a wood-grained decorative fiberglass tissue, available from Lance Brown Import-Export can be molded into the door member. Alternatively, the wood-like texture can be a stainless steel foil bag, available from McMaster-Carr. The stainless steel foil bag is properly shaped to have door-like edges. In addition, an insertable door member can be CNC machined and coated with a topcoat, primer or sealer.

[0048] Another embodiment of the present invention is illustrated in FIG. 5 as having a pre-pigmented plastic door shell 84. Preferably, the pre-pigmented plastic door shell 84 is fabricated using a blow molding method. However, it is understood that other fabrication processes can be used depending on the application. These fabrication processes can include rotomolding, sheet extruding, injection molding or thermoforming. A particularly useful sheet extruding method includes forming a biaxially oriented sheet, trimming and notching the biaxially oriented sheet, and fastening a pre-formed door member to the biaxially oriented sheet by using adhesives or ultrasonic welding. A particularly useful injection molding process includes injection molding sections of the door frame and fastening the sections together to form the door frame. Examples of pre-pigmented plastics include polystyrene, polyvinyl chloride, polyethylene terphthalate, polyolefins, nylon, ABS, ABS-(ABS-glass fiber)-ABS composites, long fiber thermoplastics, reinforced plastics, and blends of these plastics. Preferably, ABS is used. Pre-pigmenting gives a uniform surface color and painting is not necessary.

[0049] An elongated insert 86 can be placed along inner edge 88 through a hole 90, as illustrated in FIG. 5. Elongated insert 86 can be up to the height of the pre-pigmented plastic door shell 84. First hinge plate 92 and second hinge plate 94 can be secured to elongated insert 86 by using a screw, nail, or similar fastener. Lock apparatus 96 can be secured to lock insert 98 by using a screw, nail or similar fastener.

[0050] A first set of hollow inserts 102 and a second set of hollow inserts 104, as illustrated in FIGS. 6 and 7, can be inserted into pre-pigmented plastic door shell 84 after the door member is placed within the interior door cavity or the foamed cement slurry cures within the interior door cavity. As illustrated in FIG. 7, the inserts 102 and 104 screw into the door member and are held in place by screw threads 78. First hinge plate 92 and second hinge plate 94 can be secured to inserts 102 and 104 by using a screw, nail or similar fastener. Two inserts are shown for simplicity. The number and spacing of the inserts will be dependent on the style of the hinge plate to be affixed thereto.

[0051]FIG. 8 depicts a preferred method of filling the interior door cavity with the foamed cement slurry and curing the foamed cement slurry to produce the gas-entrained cementitious core. It is understood that a flexible, non-ceramic compound can be introduced into the interior door cavity before filling to enhance the flexibility of the resulting high performance door. According to FIG. 8, a bank 110 of door shells are placed on platform 112 with an orientation such that the rails are parallel with the ground. Preferably, the first rail includes a pour hole 114. It is understood, however, that the door shells may be placed in any orientation conducive to introducing the foamed cement slurry into interior door cavity. These orientations include, but are not limited to, having stiles parallel with the ground and having door skins parallel with the ground. After being placed on platform 112, the series 110 of door shells are clamped into fixture 116, using a range of pressure between about 0.1 lbf/in² and about 20 lbf/in². Preferably, fixture 116 uses a range of pressure of between about 0.5 lbf/in² and about 2.0 lbf/in². Suitable fixtures for use with the present invention include a platen press, a bladder press, a pod press, a lamination line, and an edge clamp. Preferably, fixture 116 is comprised of a platen press that has a platens 118 and 120. The temperature of the platens can be between about −2° C. and about 95° C. Preferably, the temperature of the platens is between about 20° C. and about 30° C.

[0052] Nozzle 122 is preferably inserted within the interior door cavity through pour hole 114. Preferably a plurality of vent holes and grooves are included in the bottom end rail to prevent significant pressurization during pouring of the foamed cement slurry. It is also understood that no end rail is required during pouring and may be added later or not at all. Nozzle 122 delivers the foamed cement slurry into interior door cavity. The foamed cement slurry can be transferred into interior door cavity incrementally, using between 1 and 5 increments. Preferably, 1 to 3 increments are used to fill interior door cavity 16 with the foamed cement slurry. Most preferably, 1 increment is used to fill interior door cavity 16.

[0053] Alternatively, as illustrated in FIG. 9, the filling process can include placing door shell 128 such that the door skin(s) are generally parallel to the ground. After the interior door cavity is filled with the foamed cement slurry, a set of rollers 130 can be run over one of the door skins 132 to remove excess gas-entrained cementitious material 134 from the interior door cavity.

[0054] If the foamed cement slurry includes an insulating gas, the following procedure is preferably utilized. The foaming agent is pre-blended in an evacuated pressure vessel. The insulating gas is introduced into the evacuated pressure vessel. The other ingredients, which can include cement, water, setting accelerator, and water reducer, are mixed in a colloidal mixer and a ribbon mixer that are enclosed and evacuated to limit the presence of air. Once the other ingredients are sufficiently mixed in the evacuated ribbon mixer, the pre-blended foaming agent/insulating gas mixture is introduced.

[0055] The door skins are preferably secured to the walls of a holding fixture by evacuating the holding fixture. The door frame preferably has a first rail with a pour hole. An air lock is placed at the pour hole, and the interior door cavity is evacuated after the holding fixture evacuation. The vacuum pressure between the fixture vacuum holding the skin to the holding fixture walls is at least about 1 mm Hg greater than the vacuum of the interior door cavity. The foamed cement slurry, containing the entrained insulating gas is then pumped into the interior door cavity through the air lock, minimizing the contamination of the slurry with ambient air.

[0056] The pore size of the entrained insulating gas or air can be influenced. During curing, the fixture can be warmed in a convective, dialectric, or microwave oven until the cementitious reaction has allowed the cement to form a structurally stable cell wall around entrained gas and/or air bubbles. The residence time in the oven necessary to achieve a stable cell wall depends on the formulation of the foamed cement slurry, including the cement and setting accelerator used, and the oven temperature. For air, the oven temperature can range from about 1° C. to about 70° C. above ambient, preferably about 10° C. to about 40° C., and most preferably about 20° C. to about 35° C. For other gases, the range can vary depending on the mass and the molecular weight of the insulating gas.

[0057] During the curing process, a hydration reaction occurs within the foamed cement slurry. This reaction increases the amount of heat in the interior door cavity. In a typical bank 110 of 12 doors placed within the fixture, the foamed cement slurry temperature in the interior door cavity may reach about 60° C. above ambient within about six hours of curing. After the structurally stable cell wall is achieved, cooling may be added to reduce excess pressure from the expanded entrained gas. Conventional heat exchangers can be used to conserve energy during this process.

[0058] Air vibrators 124 and 126 can be attached to fixture 116 to induce improved flow and consolidation of the foamed cement slurry so as to avoid voids caused by bridging of the foamed cement slurry. Air vibrators 124 and 126 may also assist in decreasing the viscosity of the flow in foamed cement slurries that include thixotropic agents. Preferably, a US13 air vibrator, available from Global Manufacturing of Little Rock, Ark. can be employed. Preferably, the US13 air vibrator is employed for between about 2 seconds to about 30 seconds. Most preferably, the US13 air vibrator is employed for between about 5 seconds to about 10 seconds, during each incremental addition of the foamed cement slurry.

[0059] If the door skins are constructed of fiberglass and the tensile strength of the skins is less than about 1.0×10⁶lbf/in², it is preferable to apply a vacuum from the fixture 116 to the outer surface of the door skin(s) in order to hold the door skins flat during poring. The fixture draws about 5 psi to about 20 psi vacuum. The fixture surfaces preferably have grooves to allow air trapped in the vacuum ports to escape out of the edges of the fixture.

[0060] Once interior door cavity is filled with the foamed cement slurry, a cap can be secured to the first rail. The filled door shell may be capped with a top rail of thermoplastic polymer, thermoset polymer, or metal. Alternatively, the cap can be constructed of trimmable wood, optionally coated with a waterproof coating, preferably PERMAX 803, produced by Noveon, Inc., Cleveland, Ohio.

[0061] Once the interior door cavity is filled with the foamed cement slurry, the foamed cement slurry is allowed to cure in fixture 116. The foamed cement slurry reaches an initial set point once it either resists slumping, or passes through an exothermic maximum generated during the hydration reaction, whichever comes first. After reaching the initial set point, the foamed cement slurry further cures to reach a final set point in which the door can be moved without damaging the door member. Depending on the foamed cement slurry formulation, the initial set point and the final set point vary. In Example 3 below, exothermic temperature profiles are provided for two different formulations, showing the variations in the initial and final set points. Using ASTM method C-403, the door can be removed from the fixtures when the penetrometer indicates the foamed cement slurry of Example 1 achieves a strength about 70 lbf/in². It is also understood that these compressive strengths are not identical with compressive strength measurements obtained by ASTM C-39 (results described later).

[0062] Depending on the formulation, the foamed cement slurry can be cured in the fixture for a period of between about 1 minute and about 48 hours. Preferably, the cure time in the fixture is between about 5 minutes and about 24 hours. Most preferably, the cure time in the fixture is between 10 minutes and about 24 hours. The process of curing the slurry until the door can be removed from the fixture without damage is referred to as green-strength curing.

[0063] To reduce curing time, a rapid-cure setting accelerator can be added to the foamed cement slurry. The rapid-cure setting accelerator is preferably injected into the stream of foamed cement slurry at the end of nozzle 122 with a discharge tube. The discharge tube preferably includes a check valve to minimize back flow of the foamed cement slurry into the discharge tube. The typical rapid-cure setting accelerator has a basic pH of between about 11 and about 13. General examples include aluminum based accelerators, modified sodium silicate based accelerators, liquid alkali based accelerators, and alkali-free accelerators based on calcium oxide. These accelerators are discussed in U.S. Pat. Nos. 6,221,151 and 6,025,404, which are incorporated by reference. The cure time is reduced to between about 2 minutes to about 10 minutes by using the rapid-cure setting accelerator.

[0064] After emerging from the fixture, the foamed cement slurry can be further cured to achieve increased strength and final setting. The cure time after emerging from the fixture can be from about 0 days to about 100 days, preferably about 3 to about 28 days, and most preferably about 10 days to about 28 days. The typical range of compressive strengths measured using ASTM C-39 of a door member constructed of the foamed cement slurry is about 58 lbf/in² to about 75 lbf/in².

[0065] Having generally described the present invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.

EXAMPLE 1 AND COMPARATIVE CHART A

[0066] A preferred foamed cement slurry of the present invention which is capable of being cured for use as a door member comprises the following: TABLE 1 Component As-Is/Dry Weight % Hydraulic cement 61.43% Water 26.30% Foaming solution 9.22% Water reducer 0.01% Setting Accelerator 0.04% Reinforcement fibers 0.18% Expanded polystyrene beads 2.82%

[0067] The preferable hydraulic cement is Portland Cement Type III, produced by Lone-Star Industries, Inc. of Indianapolis, Ind. The preferable water is tap water. The foaming solution is preferably comprised of 1 part foaming agent and 40 parts water. The preferable foaming agent is MEARLCRETE foam liquid concentrate, produced by Cellular Concrete LLC of Roselle Park, N.J. The preferable water reducer is RHEOBUILD 100, produced by Master Builders Technologies of Cleveland, Ohio. The preferable setting accelerator is POZZOLITH NC574 of Master Builders Technologies of Cleveland, Ohio. The preferable reinforcement fibers are STEALTH {fraction (3/4)} inch long polypropylene fibers, produced by the Fibermesh Division of Synthetic Industries of Chattanooga, Tenn. The preferable nominal diameter of the expanded polystyrene beads is {fraction (1/4)} inch and are available from the Cellofoam Company of Conyers, Ga.

[0068] A preferred method of mixing the ingredients of the foamed cement slurry comprises the following steps. The water, hydraulic cement, setting accelerator, and reinforcement fibers are added to a colloidal mixer supplied by Chem Grout of LaGrange Park, Ill. Preferably, the four ingredients are added to the colloidal mixer in that order. Upon mixing the ingredients for at least 45 seconds (to ensure substantial mixing of the hydraulic cement and the water), the water reducer is added to the colloidal mixer. By waiting at least 45 seconds to add the water reducer, the effectiveness of the water reducer is greatly enhanced. After mixing the water reducer with the other four ingredients, the contents of the colloidal mixer is transferred to a ribbon mixer preferably supplied by Chem Grout of LaGrange Park, Ill. In a foaming agent mixer, the foaming agent, water, and air are mixed to form the foaming solution. Preferably, the foaming solution is added to the ribbon mixer, with the addition of the expanded polystyrene beads following. The ribbon mixer is preferably modified to include t-bars to assist in blending the contents of the ribbon mixer.

[0069] A preferred method of transferring and curing the foamed cement slurry comprises the following steps. Before the interior door cavity is filled with the foamed cement slurry, the door shell is clamped into a platen press using a force of about 0.5 lbf/in² to about 2.0 lbf/in². The temperature of the platens is in the range of about 20° C. to about 30° C. Once the contents of the ribbon mixer are substantially blended, a Moino pump is preferably used to pump the foamed cement slurry into the interior door cavity. The Moino pump does not excessively compress air bubbles entrained in the foamed cement slurry so as to destroy the foaming action of the foaming solution. The foamed cement slurry is transferred into the door shell in 1 to 5 increments, preferably 1 to 3 increments, and most preferably 1 increment until the interior door cavity is filled. The filled door is allowed to cure in the platen press until the foamed cement slurry does not slump. The cure time in the press fixture is preferably from about 6 hours to about 10 hours.

[0070] It is also understood and preferable to transfer foamed cement slurry and fill the interior door cavity by means of a gravity feed system. In this system, the contents of the ribbon blender are poured under the force of gravity into a hopper. The hopper is mechanically positioned over the interior door cavity. The foamed cement slurry is allowed to flow from the hopper into the interior door cavity. The advantage of this system is cost reduction by limiting the destruction of bubbles passing through the compressive phase of the pump.

[0071] Various foaming agents were tested using the foamed cement slurry of Example 1 and substituting various foaming agents. One test included pouring the foamed cement slurry into an about 10 foot high by about 4.5 inch diameter column. The slurry was leveled off flush with the top of the column. The most preferable foams would allow the foamed cement slurry to avoid shrinking or permanently expand by more than about 2 millimeters during setting so that the cement column was actually higher than the top of the column when observed after about 8 hours of curing.

[0072] Another test includes foaming various foaming agents with air in a five gallon HDPE pail container. Preferably, a “Junior” foam generator supplied by EAB Associates, Altrincham, United Kingdom is used to foam the foaming agent. An 85 gram plate load with a diameter of about 5.25 inches is placed on top of the foam. If the load remains visible above the foam after about one hour, otherwise referred to as persistence time, the foam is suitable for the manufacture of at least about eight foot high doors.

[0073] The following table includes the test results for various foaming agents: CHART A Foaming Column Persistence Foaming agent agent type expansion time (hrs) EABASSOC Synthetic N/A 0.5 PS 1262 Protein-based Shrinkage 3 Mearlcrete Protein-based Expansion >3 AFTC101251 Synthetic Expansion >3 RHEOCELL 15 Synthetic N/A 0.2

[0074] It should be understood that the column expansion was not measured for EABASSOC and RHEOCELL 15 since the persistence time was too short to accommodate such a measurement.

[0075] EABASSOC is available from EAB Associates of Altrincham, United Kingdom. PS 1262 foaming agent is available from Master Builders Technologies of Cleveland, Ohio. Mearlcrete is available from Cellular Concrete L.L.C. of Roselle Park, N.J. AFTC101251 is available from Applied Foam Tech Corporation of Harleysville, Pa. RHEOCELL 15 is available from Master Builders Tech.

[0076] The synthetic foaming agents are suitable for use with superplasticizers to increase flowability of the foamed cement slurry. A preferred combination of foaming agent and superplasticizer is RHEOCELL 30 and RHEOBUILD HRWR 3000 FC.

EXAMPLE 2

[0077] Example 2 is a low cost variation of the foamed cement slurry in Example 1. To reduce the cost of the foamed cement slurry, a foaming solution is substituted for expanded polystyrene beads. The foamed cement slurry of Example 2 comprises the following: TABLE 2 Component As-Is/Dry Weight % Hydraulic cement 59.20% Water 25.33% Foaming solution 15.24% Water reducer 0.01% Setting Accelerator 0.04% Reinforcement fibers 0.18%

[0078] The preferable ingredients are the same as the preferred ingredients of Example 1. The preferred mixing process for the low cost variation of the foamed cement slurry is similar to the mixing process of Example 1, except that expanded polystyrene beads are not added to the ribbon mixer. The preferred method of transferring and curing the low cost variation of the foamed cement slurry is similar to the transferring and curing process of Example 1, except that the preferable curing time in the press fixture is between about 16 hours and about 24 hours. This example passes both ASTM 2074-00 and BSI 476/22 fire tests. Comparative Chart B gives density gradient data for examples 1 an 2. CHART B Height From Bottom Of Density (lb/in³) Density (lb/in³) Column Example 2 Example 1 0 ft 23.24 24.32 1 23.31 23.58 2 22.55 24.35 3 22.80 24.73 4 22.67 24.03 5 22.69 24.16 6 22.83 23.13 7 22.30 22.65 8 21.73 22.29 9 21.32 21.66

EXAMPLE 3 AND COMPARATIVE CHART C

[0079] A preferred foamed cement slurry of the present invention includes Portland Cement Type I hydraulic cement. Portland Cement Type I is a low cost alternative to Portland Cement Type III since Type I is not as finely ground as Type III. The preferred cement slurry of example 3 is comprised of: TABLE 3 Component As-Is/Dry Weight % Hydraulic cement 62.04% Water 26.88% Foaming agent 7.99% Water reducer 0.02% Accelerator 0.04% Polypropylene fibers 0.18% Expanded polystyrene beads 2.85%

[0080] The preferable ingredients are the same as the preferred ingredients of Example 1, except that the preferred hydraulic cement is Portland Cement Type I produced by Lone-Star Industries, Inc. of Indianapolis, Ind. The preferred mixing process for the foamed cement slurry of Example 3 is similar to the mixing process of Example 1. The preferred method of transferring and curing the foamed cement slurry of Example 3 is similar to the transferring and curing process of Example 1, except that the preferable curing time in the press fixture is between about 16 hours and about 24 hours. It is understood that this curing process can be quickened by increasing the temperature of the cure above ambient. At a cure temperature of about 30° F. above ambient temperature, the cure times are reduced by 50%.

[0081] Portland Cement Type III is a finer grained cement than Type I. As a result, the foamed cement slurry using Type III, achieves its final set point about two hours earlier than the foamed cement slurry of this using Type I. The exothermic temperature profiles of the two foamed cement slurries confirm these results: CHART C Example 1 Example 3 Time (min.) (using Type III) (° F.) (using Type I) (° F.) 0 67.6 65 30 69.4 68 60 70.7 70.2 90 72.3 72.6 120 74.1 74.6 (Initial set) 150 76.6 78.2 (Initial set) 180 79.8 82.2 210 84 87.4 240 89.6 94.8 270 98.6 103.2 (Final set) 300 110.8 112.8 330 117.3 117.6 360 118.3 119.6 390 119.3 120.2 (Final set) 420 118.9 119.6 450 117.3 118.6

EXAMPLE 4

[0082] A preferred foamed cement slurry of the present invention which is capable of being cured for use as an door member and is particularly suitable as a fire resistant door comprises the following: TABLE 4 Component As-Is/Dry Weight % Hydraulic cement 65.59% Water 28.67% Foaming solution 3.95% Water reducer 0.01% Accelerator 0.04% Polypropylene fibers 0.33% Expanded polystyrene beads 1.42%

[0083] The preferable ingredients are the same as the preferred ingredients of Example 3, except that the preferable foaming agent is RHEOCELL 15, available from Master Builders Technologies, of Cleveland, Ohio and the preferable water reducer is RHEOBUILD HRWR 3000 FC, available from Master Builders Technologies, of Cleveland, Ohio. The preferred mixing process for the foamed cement slurry of Example 4 is similar to the mixing process of Example 1. The preferred method of transferring and curing the foamed cement slurry of Example 4 is similar to the transferring and curing process of Example 1, except that the preferable curing time in the press fixture is between about 16 hours and about 24 hours.

[0084] The fire resistant door using the preferred foamed cement slurry of example 4 passes the 20 minute ASTM 2074-00 positive pressure fire test and the 30 minute BSI 476/22 positive fire test.

EXAMPLE 5

[0085] A preferred foamed cement slurry of the present invention which is capable of being cured for use as an door member and has a relatively low slump value and a relatively low flow rate: TABLE 5 Component As-Is/Dry Weight % Hydraulic cement 61.43% Water 26.30% Foaming solution 9.22% Water reducer 0.01% Setting accelerator 0.04% Polypropylene fibers 0.18% Expanded polystyrene beads 2.82%

[0086] The preferred ingredients are the same as the preferred ingredients of Example 1. The preferred mixing process for the foamed cement slurry of Example 5 is similar to the mixing process for Example 1.

[0087] The foamed cement slurry is suitable for continuously casting slabs on a horizontal belt into an open-faced form, using a hydrostatic head pressure feed of at least about 6 feet. A mechanical spreader, a scree, or an embossment unit is preferably used to distribute the foamed cement slurry in the form and to prepare the cured foamed cement slurry for the door frame. The preferred curing time in the open-faced form is between about 8 hours and about 16 hours.

EXAMPLE 6

[0088] A preferred high performance door of the present invention is constructed to inhibit the transfer of heat through the door member during a fire. The preferred high performance door according to this example limits the temperature of the door surface not exposed to the fire to 250° C. after 30 minutes, using the ASTM E-152 standard. The door shell is constructed of SAE 1010 carbon steel or similar material.

[0089] The door member is comprised of a cured foamed cement slurry. The foamed cement slurry is comprised of: TABLE 6 Component As-Is/Dry Weight % Hydraulic cement 65.14% Water 24.43% Foaming solution 10.07% Water reducer <0.01% Setting accelerator 0.02% Polypropylene fibers 0.33%

[0090] The preferable ingredients are the same as the preferred ingredients of Example 3. The preferred mixing process for the foamed cement slurry of Example 6 is similar to the mixing process of Example 2.

[0091] The foamed cement slurry is transferred into a form, which is sized similar to the door shell. The form is preferably made of an ultrahigh molecular weight polyethylene material. The form may have embossment patterns to match patterns present on a door shell. The foamed cement slurry is transferred into the form in 1 to 5 increments, preferably 1 to 3 increments, and most preferably 1 increment until the form is filled.

[0092] After curing the foamed cement slurry in the form from about 10 days to about 28 days, the cured foamed cement core, or door member, is stripped from the form. An adhesive is applied to the door member sufficient to hold the door member to the interior of the steel door shell. Moreover, sufficient adhesive is applied to the door so that it survives code-required slam durability tests (ANSI/ISDI 105). A typical test requires that the door last for 1,000,000 slam cycles and the adhesive should be applied to at least 70% of the surface area of the insulating core member. Preferably, the adhesive is an elastomeric latex adhesive, such as PPG TRIMBOND T7850, available from PPG Industries. Other adhesives include hot melt polyurethane, epoxy, and structural silicon caulk.

EXAMPLE 7

[0093] A preferred method of producing a high performance door of the present invention includes transferring a rapid-cure setting accelerator into the interior door cavity to greatly reduce the curing time. The foamed cement slurries of Examples 1-6 can be used in the rapid-cure method of Example 7 if the setting accelerator of Examples 1-6 is substituted with the rapid-cure setting accelerator. The preferable rapid-cure setting accelerator is shotcrete, otherwise referred to as gunite, available from various suppliers.

[0094] The preferred mixing process for the rapid-cure method is similar to the mixing processes of Examples 1-6, except that the setting accelerator is not added to the colloidal mixer.

[0095] A preferred method of transferring and curing the foamed cement slurry comprises the following steps. Once the contents of the ribbon mixer are substantially blended, a Moino pump is preferably used to pump the foamed cement slurry into the interior door cavity or the open-faced form. The Moino pump does not excessively compress air bubbles entrained in the foamed cement slurry so as to destroy the foaming action of the foaming solution. The rapid-cure setting accelerator is preferably injected into the foamed cement slurry as the slurry exits the Moino pump at a nozzle head. Preferably, a discharge tube is used to inject the rapid-cure setting accelerator. To avoid back flow of the foamed cement slurry into the discharge tube, the end of the discharge tube preferably includes a check valve. The set time is preferably from about 2 minutes to about 10 minutes. COMPARATIVE EXAMPLE 8

[0096] In foamed cement slurry formulations containing expanded polystyrene beads, an optimum amount of foaming solution should be added to reduce destruction of foam bubbles entrained in the foamed cement slurry. The following table discloses a foamed cement slurry containing 37 parts by volume expanded polystyrene beads to 63 parts by volume foaming solution: TABLE 7 Component As-Is/Dry Weight % Hydraulic cement 61.43% Water 26.29% Foaming solution 9.22% Water reducer 0.01% Setting accelerator 0.04% Polypropylene fibers 0.18% Expanded polystyrene beads 2.82%

[0097] If the formulation in Table 7 is used, an additional 22.8 parts by volume of foaming solution should be added relative to the volume of expanded polystyrene beads to reach the optimum level of foaming solution.

[0098] The following table discloses a foamed cement slurry containing 18 parts by volume expanded polystyrene beads to 82 parts by volume foaming solution: TABLE 8 Component As-Is/Dry Weight % Hydraulic cement 61.02% Water 26.12% Foaming solution 11.26% Water reducer 0.01% Setting accelerator 0.04% Polypropylene fibers 0.18% Expanded polystyrene beads 1.37%

[0099] If the formulation in Table 8 is used, an additional 14 parts by volume of foaming solution should be added relative to the volume of expanded polystyrene beads to reach the optimum level of foaming solution.

[0100] While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. 

What is claimed is:
 1. A high performance door comprising: a door shell having a generally planar construction with marginal edges and at least one door skin helping to define an interior door cavity; and a door member disposed within the interior door cavity, the door member being constructed of a gas-entrained cementitious material.
 2. The high performance door of claim 1, wherein the door member has a compressive strength of at least about 30 lbf/in² when measured using ASTM C-39.
 3. The high performance door of claim 1, wherein the door member has a density greater than about 2.6 lb/ft³.
 4. The high performance door of claim 1 wherein the door shell is comprised of a door frame and a first door skin and a second door skin.
 5. The high performance door of claim 1 wherein the door shell is comprised of pre-pigmented plastic.
 6. The high performance door of claim 1, wherein the high performance door is fire resistant for a 20 minute fire rating test using ASTM 2074-00, UL 1° C., or UBC 7-2-1997 testing standards.
 7. The high performance door of claim 1, wherein the high performance door is fire resistant for a 30 minute fire rating test using the BSI 476/22 testing standard.
 8. The high performance door of claim 1, wherein the high performance door has a security rating of grade 20 according to ASTM F-476.
 9. The high performance door of claim 1 wherein the door shell is comprised of a casing and the casing is positioned over the door member and is secured with a securing means.
 10. The high performance door of claim 1 wherein the door shell is comprised of metal and is secured to the door member with an adhesive.
 11. The high performance door of claim 1, wherein the door member is a cured product of a foamed cement slurry.
 12. The high performance door of claim 11, wherein the foamed cement slurry is comprised of a hydraulic cement and water.
 13. The high performance door of claim 12, wherein the foamed cement slurry further comprises a foaming agent.
 14. The high performance door of claim 13, wherein the foamed cement slurry further comprises at least one ingredient selected from the group consisting of a water reducer, a setting accelerator, and reinforcement fibers.
 15. The high performance door of claim 12, wherein the hydraulic cement includes a pozzolanic additive.
 16. The high performance door of claim 12, wherein the hydraulic cement includes a cementitious additive.
 17. The high performance door of claim 15, wherein the pozzolanic additive is selected from the group consisting of Class C fly ash, Class F fly ash, pulverized-fuel fly ash, condensed silica fume, metakaolin, rubber ash, and glass cullet.
 18. The high performance door of claim 1 wherein the door shell is comprised of an aesthetic layer applied to the door member.
 19. The high performance door of claim 18 wherein the aesthetic layer is comprised of a wood-like aesthetic layer.
 20. The high performance door of claim 18 wherein the aesthetic layer is comprised of an aesthetic surface layer.
 21. The high performance door of claim 18 wherein the aesthetic layer is comprised of a pre-pigmented aesthetic layer.
 22. The high performance door of claim 18 wherein the aesthetic layer is selected from the group consisting of wood veneers, decorative films, transcribed pigment layers, polyvinylidene chloride coated wood and organic polymer coating.
 23. A method for forming a door member for use in conjunction with a door, the method comprising: providing a form having a generally planar construction wherein the material used to construct the form does not readily adhere to a gas-entrained cementitious material; filling the form with the gas-entrained cementitious material; green-strength curing the gas-entrained cementitious material; and removing the cured gas-entrained cementitious material from the form wherein the cured gas-entrained cementitious material provides a gas-entrained cementitious core for use in conjunction with a door.
 24. The method of claim 23 wherein the gas-entrained cementitious material is comprised of a foamed cement slurry.
 25. The method of claim 23, wherein the Material used to construct the form is selected from the group consisting of ultrahigh molecular weight polyethylene, high density polyethylene, polypropylene, polycarbonate, and polyvinylidene chloride.
 26. A method for forming a door member for use in conjunction with a door, the method comprising: selecting a gas-entrained cementitious material that has flowability of between about 4.825 inches and about 18 inches when tested using the TT flowability method; casting the gas-entrained cementitious material into a form; allowing the gas-entrained cementitious material to achieve green-strength cure; and removing the gas-entrained cementitious material from the form wherein the cured gas-entrained cementitious material provides a gas-entrained cementitious material core for use in conjunction with a door.
 27. A method for forming a high performance door, the method comprising: providing a door shell having a generally planer construction with marginal edges and at least one door skin helping to define an interior door cavity; placing the door shell in a fixture; filling the interior door cavity with a gas-entrained cementitious material; green-strength curing the gas-entrained cementitious material; and removing the door shell from the fixture wherein the cured gas-entrained cementitious material provides a gas-entrained cementitious core for use in conjunction with a door.
 28. The method of claim 27 further comprising inserting a flexible, non-ceramic compound into the interior door cavity prior to filling the interior door cavity.
 29. The method of claim 27, wherein the fixture is comprised of a platen press.
 30. The method of claim 27, wherein the placing the door shell in the fixture is comprised of the following steps: placing the door shell in an orientation such that the at least one door skins is generally parallel with the ground; and running an at least one roller over one of the door skins wherein excess gas-entrained cementitious material is removed from the interior door cavity.
 31. The method of claim 27 further comprising agitating the gas-entrained cementitious material with an air vibrator to inhibit the formation of voids in the gas-entrained cementitious material.
 32. The method of claim 27, wherein the door shell is comprised of a first door skin having a first exposed outer surface and an first opposed inner surface, a second door skin having a second exposed outer surface and a second opposed inner surface, and a door frame, the door frame being attached to the first opposed inner surface and the second opposed inner surface.
 33. The method of claim 32, wherein the door frame is comprised of stiles and rails, wherein the stiles are constructed of laminated wood and the rails are constructed of high-density polyethylene-wood fiber and wherein the first door skin and second door skin are comprised of fiberglass.
 34. The method of claim 33 further comprising inserting a plurality of nails into an at least one interior edge of the stiles prior to filling the interior door cavity with the gas-entrained cementitious material; wherein the plurality of nails serve to connect the door frame to the gas-entrained cementitious core.
 35. The method of claim 32 further comprising fastening a reinforcement mat to an at least one interior edge of the door frame.
 36. The method of claim 35 wherein the reinforcement mat is comprised of a metal mesh sheet.
 37. The method of claim 36 wherein the metal mesh sheet is selected from the group consisting of chicken wire, grill cloth, aluminum screen, chain-linked fencing and expanded metal.
 38. The method of claim 35 wherein the reinforcement mat is comprised of a polymer mesh sheet.
 39. The method of claim 38 wherein the polymer mesh sheet is selected from the group consisting of polyethylene mesh, aramid fiber mat, carbon fiber mat, nylon screen, rubber-coated textiles, and plastic laminated fiber mat. 